In this preliminary observational study, we quantified the effect of noxious stimuli on these episodic EEG waveforms (10 Hz spindle-like waves and slow oscillations in high frequency power) as well as the non-episodic delta waves
, in a cohort of healthy patients undergoing general anaesthesia.
They recorded EEGs that show slow, regular waves, called delta waves
, during the deepest parts of the sleep cycle.
Stage Description Duration W Wakefulness ~16 hours N1 Somnolence; "drowsy," easily awakened 1-5% N2 Asleep -50% N3 Slow Wave Sleep ~7% (SWS) Transition to deep sleep N4 Slow Wave Sleep ~20-25% (SWS) Deep sleep REM1-4 Rapid Eye Movement ~20-25% Stage EEG Brainwave pattern Events and abnormalities W Alpha waves Daytime consciousness N1 Theta waves Hypnogogic twitches, hallucinations N2 Slower waves, sleep spindles, K-complexes Unconsciousness N3 <50% delta waves
Melatonin peak, (SWS) night terrors, parasomnias N4 >50% delta waves
Minimum core temperature, (SWS) rebounds after deprivation REM1-4 Rapid low-voltage EEG Dreaming, low muscle tone, rebounds after deprivation
Electrical brain activity during the concentration stress test was significantly increased for both theta and delta waves
in the Neuravena group, researchers noted.
The researchers calculated the power ratio of alpha waves to theta waves (A/T); the ratio of alpha waves to delta waves
(A/D); and the ratio of alpha waves to the sum of theta and delta waves
The brain begins to produce delta waves
, a type of wave that is large (high amplitude) and slow (low frequency).